In typical networked-based commerce systems, a buyer can enter a commerce system's web-site and from the listings published in the web-site, select a desired listing and participate in the bidding process, if the listing is on auction.
Typically, the buyer bids by entering the website and watching the last bid before deciding whether to bid or not. If a decision is made on bidding, or the buyer has already bid on a listing and would like to know if there is any outbid, then the only available channel is the commerce system's website. Buyers also must know if they are the winner whenever the auction is over in order to be able to proceed with other steps such as payment for their desired listing.
Sending messages from the market place to the bidders, e.g. for announcing the end of an auction, is commonly conducted via electronic mail messaging. Currently, real-time messaging has gained a lot of support from several service providers and has become a very popular method of communication. Real-time messaging, also known as instant messaging (IM), uses a client program to hook up to an IM service to provide the client with a IM messaging capability. Most services present features, such as presence information, indicating whether anyone on the contact list of a user is currently online and available for chat.
Presently, several instant messaging services are available on the public internet. The list of most popular ones include, QNEXT®, WINDOWS® Live Messenger, AOL® Instant Messenger, YAHOO® Messenger, GOOGLE® Talk, SKYPE®, .NET® Messenger Service, JABBER®, and ICQ®. Instant messaging increases communication and provides for easier collaboration. On most systems, the user can set an online status or away message to let peers know whether the user is available, busy, or not present at the computer.
Numerous standards for instant messaging have been introduced and used by various providers and several attempts to unify the standards have failed. These standards include, IETF's SIP (Internet Engineering Task Force's Session Initiation Protocol) and SIMPLE (SIP for Instant Messaging and Presence Leveraging Extension), APEX (Application Exchange), and IMPS (Instant Messaging and Presence Service).
While standard instant messaging typically involves an IM server, Peer-to-Peer (or P2P) instant messaging relies primarily on the computing power, storage, and bandwidth of the participating users available on the network. As such, the notion of client-server does not apply to P2P networks. The P2P network systems, having a distributed nature, increase the robustness of the network by replacing centralized servers with a cluster of network nodes (computers). The connections between nodes in a P2P network are typically ad hoc connections.
Many P2P networks using overlay protocol are examples of overlay networks. Overlay networks are computer networks built on the top of the internet; the construction of which allow routing of messages to the destinations not specified by IP (Internet Protocol) addresses. Based on how the nodes in an overlay network are linked to each other, one can classify the P2P networks as unstructured or structured. If the overlay links are arbitrarily established, then the network is unstructured. Most popular P2P networks such as NAPSTER®, GNUTELLA®, KAZAA®, and SKYPE® are unstructured.
Structured P2P networks on the other hand maintain a Distributed Hash Table (DHT) and allow for each peer to be responsible for a specific part of the content on the network. Some well known structured P2P networks are: CHORD®, PASTRY®, TAPESTRY®, CAN®, and TULIP®.
Real time communication between a network-based commerce system and its clients is a challenge in existing systems For example, the sending of alert notifications and the receiving of client responses to the communicated alert notifications is an example of the challenges that many electronic commerce systems face today.